Spot welder tip



July 22, 1941.

K. F. BOHN SPOT WELDER TIP Filed Sept. 30, 1940 MIN Patented July 22,1941 sro'r wELnsn TIP Karl F. Bohn, Lockport, N. Y; assignor to GeneralMotors Corporation, Detroit, Mich., a cornotation of DelawareApplication September 30, 1940, Serial No. 358,968

4 Claims.

This invention relates to an improved welding tip and holder assemblydesigned to eliminate difllcultles experienced in spot welding interiorbailies, filler necks and other appurtenances to tanks of automobileradiators. To reach into restricted space often presented, electroderods of proper length have been forged to special shapes so as toestablish welding contact at the necessary points. In factory productionwith the weld ing apparatus in continuous use the tips need to bereforged from time to time, particularly because of the lack ofstiffness and also because of accelerated wear resulting from poorcooling.

It is an object of the present invention to provide a sturdy but compacttip and holder assembly for use in close quarters with provision forcarrying away excess heat and which will have a long life amt need aminimum of attention in USE.

ciilcation having reference to the accompanying drawing wherein Figure 1is an elevation ofthe improved tip and holder assembly mounted for use;Figure 2 is a perspective view of the assembly; Figure 3 is a detailsectional view on line 3--3 of Figure 1 and Figure 4 is a top plan viewon a large scale of the tip and free end of the holder.

In the drawing the numeral I indicates a sup "porting arm having acooperating cap piece 2 for holding in place a vertically adjustabl rod3 which in turn carries at its lower end a head 6 having a clamp plate 5secured thereto by studs 6 for mounting the outer end of an electrodesupporting rod or holder i. An electrode or welding tip 8 extendslaterally from the inner end of the rod 3 for cooperation with acomplementary electrode assembly indicated by broken lines in Figur 1.As will beobvious the electrode tip may be adjusted to various.positions through the settings of the clamp plates 2 and 5. Theelectrode 8, which may be formed from a solid piece of copper rodmachined to shape, has one end converging to the welding tip or pointand the portion adjacent its other end formed for inter- 'in thedirection of its axis.

locking connection with the free end of the supporting rod 1.

For this purpose the free end of the rod 1! is formed with an arcuateseat, indicated at 9, to receive a similarly shaped seating surface ofthe electrode 8 and is also provided with a pair of diametricallyopposite axially extending grooves at the sides to receive the legs IDof a hairpin shaped wire retainer whose bight ll embraces the electrode8 and is fitted into a peripheral groove in the side of the electrodeopposite its rod engaging seat. The hairpin retainer not only holds theparts in seating engagement and against lateral displacement but byreason of its reception within the keyways or grooves mentioned, locksthe electrode against dislodgment Immediately adjacent the bight or loopH the wire retainer straight/ens out to form the-legs iii-I0 and thesestraight portions engage oppositely disposed ilats or side faces on theelectrode 8 whereby turning of the electrode on its axis is prevented.For adjusting and anchoring the hairpin retainer the free ends of itslegs iii are curled to form eyes which are fitted to lateral pins on thenut 12 threaded on the adjusting screw I3. At one end the adjustingscrew carries a hand wheel l4 and at its opposite end has a bearingblock l5 engaging the outer end of the rod 1. Rotation of the hand wheelor knob M in one direction tensions the legs I0 01 the hairpin retainerfor securely anchoring the electrode to its holder while rotation in theopposite direction shifts the retainer in the rod keyways to move thebight ll away from the seat 9 when replacement of the electrode tip isnecessary.

Heat from the solid electrode 8 is transferred through the seat 9 and iscarried away by cooling liquid circulating through the rod. To providecirculating passages the rod 1 is drilled from its outer end to a pointadjacent the seat 9 forming a circular opening or hollow space i5{throughout the rod. This space is divided into two channels by a baflleor partition wall I1 extending through the hollow rod 1 fromitsouter endto a point spaced or stopped short of the inner end of the passage Itfor communicating the channels on opposite'sides of the wall ll. Aconvenient way of locating the wall I1 is to project at given intervals9. pair of spaced pins l8 through the wall of thehollow rod 1 and intothe interior passageway on both sides of the dividing wall as best shownin Figure 3. The outer end of.-the passageway is closed by a stopper orplug [9 and a pair of elbow fittings d 25 are provided communicate theree channels W1 3 heee or conduits zeoling liquid,

eleetrade tip there are no mud leexage mile the zelid with afiely, lessme- 2212 welding brie rod including eight fitted within p and its sidelegs recesses in the at connected with aving screw thread- ".l/ andbearing on the I11 welding a evlce, a supporting rod havieenbl'ani; seatat its inner end, an elecha-ving a. flat side,

- J erode fitted in said seat and a. clamping memb enge i seer embracingJ3. posite lee retainer l1 to clamp e "rel :tip thereto, 9.

laterally project elect; er aging said seat and hem a peripLera ocatinggroove receiving the embracing Jhe retainer to ment azdally of the tipand m ans :onnected with the red. Mr legs for shifting the bightrelative to said seat.

KARL F. BOHN.

